An organic light emitting phenomenon refers to a phenomenon of converting electrical energy to light energy using an organic material. That is, when positioning an appropriate organic layer between an anode and a cathode, and then applying a voltage between two electrodes, holes are injected into the organic layer from the anode and electrons are injected into the organic layer from the cathode. Excitons are generated when the injected holes and electrons encounter each other, and light is generated when the excitons fall down to a lower energy state.
Since an interval between the anode and the cathode is small, an organic light emitting device (OLED) is easy to have a short-circuit defect. Due to a pinhole, a crack, a step and coating roughness in a structure of the OLED, and the like, the anode and the cathode may directly contact with each other. The thickness of the organic layer may become thinner in such a defect zone. The defect zone may provide a low resistance path in which current easily flows, thereby reducing or preventing sufficient current from flowing through the OLED in an extreme case. Accordingly, light emitting output of the OLED may decrease or disappear.
In a multi-pixel OLED, such a short-circuit defect may generate a dead pixel of not emitting light or emitting light less than the average light intensity, thereby degrading the display quality. In the case of a lighting or other low resolution usages, a large portion of the OLED device may not operate due to the short-circuit defect.
Due to concerns about the short-circuit defect, manufacturing of an OLED is generally performed in a clean room. However, even a clean environment may not effectively remove the short-circuit defect. In many cases, to decrease the number of short-circuit defects by increasing the interval between two electrodes, the thickness of the organic layer may be unnecessarily increased as compared to a thickness desired to operate the OLED. Such a method may add cost in manufacturing the OLED. Further, the method may not completely remove the short-circuit defect.